One of the least recognized aspects of tire traction considerations on a very cold day at the track, is the heat-wicking effects that very cold pavement surfaces have on your tires.
Based on observations of many crashes (while attending hundreds of cold trackdays over the years) I'm confident that lack of knowledge/recognition of this little discussed fact is a primary factor.
What do I mean?
Well let's look at it from a best-case scenario where a rider is fortunate enough to have a generator and tire warmers to use. Let's assume the rider is at a trackday where the ambient temps are in the 50's (or below, early and late in the day).
Here's a sample sequence: (note: temps are just for illustration purposes, and may or may not be actual numbers seen)
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- 1) Bike on stand after 30+ minutes on tire warmers
- Tire temp = 160 degrees
2) Warmers removed, and bike ridden through pits to staging area awaiting track going green for session:
- Tire temp = 130 degrees
3) 4 minute wait in staging area before being waved to head to hot pit, and out to track
- Tire temp = 90 degrees
4) Tires rolling over asphalt with ambient temperature of 50 degrees, with 100 MPH cold wind passing over tires at 40 degree wind-chill (or less) for 2:00+ minutes (1/2 - 1 lap), at easy pace, using minimal lean angle and limited contact on tread edges
- Tire temp = 70 degrees (at end of 1st lap)
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- 5) Rider completes 1 full lap, and figures "Hey, my tires should be kinda warmed up by now".
6) Rider leans the bike just a little further over going into Turn 3 on the start of their 2nd lap
7) Rider tucks front and crashes, with zero warning, muttering to the themselves on the way down: "WHAT THE _ _ CK??"
What's the take-away I'm trying to convey here?
- On very cold days, tires on your bike actually get COLDER ........ not WARMER than where they started ........ during the sequence of initially leaving your pits, waiting in the staging area, and heading out and around the track for the first lap or two.
Solution?:
Recognize that tire temperature actually goes through a roller-coaster ride between the time the tire warmers come off, until the tires eventually come up to the highest on-track temp that they're going to reach on that particular cold day.
-> Up : while on the warmers
<- Down : idle time before actually getting on track, and during the first lap or two
-> Up : gradually during the subsequent 2-10 laps. However likely never reaching the original roller coaster (tire warmer) peak, even at the end of the session!
Hope this posting is read by some trackday riders that'll be hitting up an event in the colder months, and at least one person will potentially avoid a "cold tire crash", as a result of a newfound recognition of these factors.
